Provided is a stereo imaging apparatus that generates X-rays from a plurality of different focal positions and that acquires a plurality of X-ray images from an X-ray detector, the stereo imaging apparatus including X-ray generation controlling means for controlling irradiated areas of X-rays so that an irradiated area in a detection area of the X-ray detector based on X-rays applied from a first focal position is included in an irradiated area in the detection area based on X-rays applied from a second focal position.